Mobile phone with humidity sensor

1. A mobile phone, comprising a casing and a cavity in the casing, the cavity being in the shape of a recess, sealed from an interior of the casing by cavity walls and connected to the exterior of the casing by a window in the casing, a humidity sensor disposed in the cavity and arranged for measuring a humidity in the cavity, wherein the humidity sensor comprises a sensitive element, said sensitive element comprising a layer for accepting water molecules from the air in the cavity, a control unit for analyzing a humidity signal supplied by the humidity sensor, and an output unit for presenting a result of the analysis.

2. The mobile phone according to claim 1 , comprising a window in the casing, said casing connecting the cavity to an exterior of the casing, wherein the cavity is arranged for receiving a humidity resulting from a transepidermal water loss when a body part of the user covers the window.

3. The mobile phone according to claim 1 , comprising a membrane permeable to air arranged in the cavity, said membrane separating the cavity into a first volume and a second volume, wherein the first volume is connected to the window and the second volume is confined by the membrane and cavity walls, and wherein the humidity sensor is arranged for measuring the humidity in the second volume.

4. The mobile phone according to claim 1 , comprising a temperature sensor arranged for measuring a temperature of a body part of a user when the body part covers the window, and in particular comprising a heat conducting element, said heat conducting element conducting heat from a surface of the casing to the temperature sensor arranged on a common carrier together with the humidity sensor.

5. The mobile phone according to claim 1 , wherein the control unit is configured for analyzing a characteristic of the humidity signal over time.

6. The mobile phone according to claim 5 , wherein the control unit is configured for determining one of a derivative of the humidity signal, a change of the humidity signal within a given time interval, and a point in time at which a given target change of the humidity signal is achieved.

7. The mobile phone according to claim 1 , comprising means for triggering the analysis of the humidity signal.

8. The mobile phone according to claim 5 , comprising means for triggering the analysis of the humidity signal, wherein the control unit is configured for storing a present humidity value as a reference humidity value in response to a trigger of the analysis, determining a skin humidity class subject to the analysis of the characteristic of the humidity signal over time, and initiating a presentation of the skin humidity class via the output unit.

9. The mobile phone according to claim 1 , wherein the control unit is configured for determining a skin humidity class subject to a change in the humidity signal and subject to a humidity value reached at the end of a given time interval.

10. The mobile phone according to claim 1 , wherein the output unit includes a display, and wherein the result is presented on the display.

11. A method for operating a mobile phone, comprising the steps of using a layer of a sensitive element of a humidity sensor disposed in a cavity of a casing of the mobile phone and arranged for measuring a humidity in the cavity, wherein the humidity sensor comprises a sensitive element comprising a layer for accepting water molecules from air in the cavity, the cavity being in the shape of a recess, sealed from an interior of the casing by cavity walls and connected to the exterior of the casing by a window in the casing, analyzing a humidity signal supplied by the humidity sensor, and presenting a result of the analysis via an output unit of the mobile phone in response to a trigger.

12. The method of claim 11 , further comprising the step of analyzing an increase in the humidity signal in response to the trigger.

13. The method of claim 11 , further comprising the step of analyzing a decrease in the humidity signal in response to the trigger.

14. A non-transitory computer-readable medium having a computer program element embodied therein in form of a plurality of instructions, wherein the plurality of instructions, when executed by a microprocessor, implements a method according to claim 11 .